-/* origin: FreeBSD /usr/src/lib/msun/src/s_tanh.c */
-/*
- * ====================================================
- * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
- *
- * Developed at SunPro, a Sun Microsystems, Inc. business.
- * Permission to use, copy, modify, and distribute this
- * software is freely granted, provided that this notice
- * is preserved.
- * ====================================================
- */
-/* Tanh(x)
- * Return the Hyperbolic Tangent of x
- *
- * Method :
- * x -x
- * e - e
- * 0. tanh(x) is defined to be -----------
- * x -x
- * e + e
- * 1. reduce x to non-negative by tanh(-x) = -tanh(x).
- * 2. 0 <= x < 2**-28 : tanh(x) := x with inexact if x != 0
- * -t
- * 2**-28 <= x < 1 : tanh(x) := -----; t = expm1(-2x)
- * t + 2
- * 2
- * 1 <= x < 22 : tanh(x) := 1 - -----; t = expm1(2x)
- * t + 2
- * 22 <= x <= INF : tanh(x) := 1.
- *
- * Special cases:
- * tanh(NaN) is NaN;
- * only tanh(0)=0 is exact for finite argument.
- */
-